In many sensing applications, the correct operation of the sensing element may require device packaging suitable for harsh sensing environments. Various approaches may be used to achieve such packaging. For example, an oil-filled construction approach may include a metal diaphragm positioned in front of the sensing element and the space between the metal diaphragm and the sensing element may be filled with an incompressible fluid such as oil. Further, an environmental condition such as pressure may be applied to the metal diaphragm with the environmental condition transferred to the sensing element using the incompressible fluid. For this approach, the metal diaphragm may protect the sensing element from the environmental condition.
For harsh, high temperature, rugged environments, a leadless packaging approach may be used to achieve alternative construction for hermetically packaging sensors such as described by U.S. Pat. No. 5,955,771, entitled “SENSORS FOR USE IN HIGH VIBRATIONAL APPLICATIONS AND METHODS FOR FABRICATING SAME,” issued on Sep. 21, 1999 to A. D. Kurtz et al. and assigned to Kulite Semiconductor Products Inc., the assignee herein. The leadless packaging approach may enable the sensing network to be hermetically protected in an inert environment, while exposing only the backside of the deflecting silicon diaphragm to the environmental condition. Although these packaging approaches are applicable for use in sensors, in many applications however, in addition to the sensor network, an electronic circuit such as signal conditioning electronics may need to be incorporated into the design, for instance, to achieve an accurate, high-level output signal.
For example, FIG. 1 illustrates a prior art electronic circuit 100 that may be integrated with a sensor. In FIG. 1, the prior art electronic circuit 100 includes a piezoresistive bridge 110 and analog interface 120. The piezoresistive bridge 110 includes piezoresistors 112 113 114 115, which are configured as a Wheatstone bridge. The analog interface 120 includes a voltage regulator 121 and an amplifier 123. The voltage regulator 121 supplies a bias voltage to the piezoresistive bridge 110. Further, the piezoresistive bridge 110 is electrically coupled to ground using a span resistor 117. The piezoresistive bridge 110 measures a pressure applied to a semiconductor diaphragm to obtain and output a pressure signal. The amplifier 123 then modifies an amplitude of the pressure signal. The prior art electronic circuit 100 of FIG. 1 is well known in the art and, for instance, reference is made to U.S. Pat. No. 7,861,597, entitled “HIGH TEMPERATURE TRANSDUCER USING SOI ELECTRONICS,” issued to A. D. Kurtz and assigned to Kulite Semiconductor Products, Inc, the assignee herein.
There is a need for techniques to allow for a sensor to be co-located with a circuit, for example, for operating in harsh environments, or over a certain temperature range. An oil-filled construction of the sensor is one possible option. However, it may require the electronic circuit such as signal conditioning electronics to be in contact with the oil in the cavity of the sensor, which may affect the performance, quality or reliability of the electronic circuit. Additionally, the use of an oil-filled construction of the sensor may also limit a temperature range of the packaged sensor due to, for instance, temperature limitations of the oil. An alternative construction or packaging of the sensor with the electronic circuit may be required to facilitate accurate device operation in harsh environments or over a certain temperature range. Accordingly, there is a need for techniques to allow for a sensor to be co-located with a circuit operating in harsh environments or over a certain temperature range.
Other desirable features and characteristics of the present disclosure will become apparent from the subsequent detailed description and claims, taken in conjunction with the accompanying figures and the foregoing technical field and background.